Difference in Germination Traits between Congeneric Native and Exotic Species May Affect Invasion.

Germination traits are components of invasion potential, and comparing seed traits in sympatric native and invasive species can offer insights into the invasion process. We characterized seed germination traits and how they influenced the success of Eragrostis mexicana, a native species, and Eragrostis tenuifolia, an exotic species (Poaceae) in Mexico, in the context of their potential for biological invasion. Seeds from both species were collected from four sites in a natural protected area in Mexico City, and the germination of seeds of different ages was conducted in experiments at different temperatures. E. tenuifolia exhibited higher germination percentages than the native E. mexicana across all treatments. Seed age had differential effects, with older seeds of the native E. mexicana germinating better, while E. tenuifolia performed better with younger seeds. Temperature positively impacted germination for both species, although E. mexicana was limited at lower temperatures. Exotic E. tenuifolia can germinate over a wider temperature range with earlier germination rates, and generate a seed bank lasting several years, which may contribute to naturalization. The importance of germination traits in the context of invasive species establishment underscores the potential role of seed banks in facilitating biological invasions.

Could non-native species boost their chances of invasion success by socializing with natives?

Most invasions start with the introduction of a few individuals and the majority fail to establish and become invasive populations. A possible explanation for this is that some species are subject to Allee effects-disadvantages of low densities-and fail to perform vital activities due to the low availability of conspecifics. We propose that 'facilitation' from native individuals to non-natives through heterospecific sociability could enhance chances of the latter establishing in novel environments by helping them avoid Allee effects and even reducing the minimum number of non-native individuals necessary to achieve the density for a viable population (the Allee effect threshold). There is evidence from experiments carried out with freshwater fish, snails, lizards, mussels and bird that supports the idea of heterospecific sociability between native and non-native species as a process to promote invasion success. We propose that to understand invasion success in social non-native species we need to investigate how they integrate into the recipient community. Furthermore, to manage them, it may be necessary to reduce population density not just below the Allee effect threshold but also to understand how natives could help them shift the conspecific Allee effect threshold to their benefit. This article is part of the theme issue 'Mixed-species groups and aggregations: shaping ecological and behavioural patterns and processes'.

Synchrony between Reproductive Phase and Flood Period: A Dispersion Mechanism for the Freshwater Clam Corbicula fluminea (Bivalvia: Corbiculidae) in a Brazilian Neotropical Floodplain.

This study evaluates the gonadal histology of Corbicula fluminea present in the upper Paraná River floodplain and samples of limnological variables to understand its reproductive cycle. Corbicula fluminea was monitored monthly from December 2013 to February 2015. Spermatogonia, primary and secondary spermatocytes, spermatids and spermatozoa were identified in the male follicles of the hermaphrodites. Oogonia, oogonial nests, previtellogenic oocytes, early vitellogenic oocytes, middle vitellogenic oocytes and full-grown vitellogenic oocytes were identified in the female follicles of the hermaphrodites and females. The reproductive phases were described as developing, active spawning/sperm releasing, regression and regeneration. Higher values of temperature, dissolved oxygen, total nitrogen and total phosphorous were identified during flood periods, while higher values of pH and conductivity were obtained during dry periods. The species either does not reproduce or reduces the intensity of reproduction in cold months, with the sex ratio not differing significantly between hermaphrodites and females with regard to month and reproductive phase. Thus, reproduction is synchronized with the flood period and its limnological characteristics and when the increase in connectivity between floodplain environments facilitates the larval dispersion of this non-native species into other environments.

Distinctive seed dispersal and seed bank patterns of invasive African grasses favour their invasion in a neotropical savanna.

High propagule availability compared to native species is often critical to invasion success, but it is unclear if this has contributed to invasions by African grasses in Neotropical savannas. We compared patterns of occurrence in the vegetation, seed rain and seed bank among African and native grasses in Cerrado sites in southeastern Brazil. In grasslands and savannas, we obtained the abundance of grasses in the vegetation, in the seed rain (monthly for one year) and in the seed bank (rainy and dry season), and assessed seed limitation and relationships among compartments. Invasive grasses showed low abundance in all compartments and high seed limitation in grasslands, where the seed bank and seed rain were dominated by small-seeded native grasses, but were at least as abundant as the natives in the seed bank and seed rain in savannas, mostly due to high abundance of Melinis minutiflora at these compartments. Native grasses dispersal occurred in the rainy season, whereas invasive grass dispersal occurred from mid rainy to mid dry season (Urochloa decumbens) and in the dry season (M. minutiflora). Melinis minutiflora showed a more persistent seed bank than U. decumbens and natives in savannas. Abundance of invasive and most of the native grasses in the vegetation was positively related to their abundance in the seed rain. Differences in seed production, the timing of seed dispersal and seed bank persistence compared to native grasses seem to favour invasive African grasses in the Cerrado, but this role may differ between grasslands and savannas.

Using molecular data to monitor the post-establishment evolution of the invasive skeleton shrimp Caprella scaura.

The study aims to monitor the post-establishment success of the invasive skeleton shrimp Caprella scaura in the Atlantic-Mediterranean transition zone and understand its connectivity with other world areas, providing new information on the status of the introduced population and its global distribution. By using mitochondrial markers (16S and COI) we examined the temporal variation of populations in Cadiz Bay, Spain (hotspot for introductions in Europe) in between 2010 and 2017; as well as their linkage with foreign populations in its native and introduced distribution ranges. Cadiz Bay populations exhibited a connection with several European introduced populations (Iberian Peninsula, Canary Islands, Mediterranean Sea and The Netherlands), eastern USA, Sea of Japan and Australia. We found no evidence to support a Brazilian origin (one potential native area) of the Iberian Peninsula populations. We identified a progressive decrease in haplotype diversity and a low connectivity at the end of the monitoring period in one of the stations. Human-mediated changes in propagule pressure, and unfavorable environmental fluctuations are probably responsible for this. Meanwhile, populations in Cadiz Bay count on numerous foreign donors that could easily refuel the propagule input by exchanging gene flow. This implies that a vector regulation strategy has the potential of compromising the success of established non-native populations, which usually undergo vulnerability periods due to the challenging conditions of marinas. The use of molecular tools in a time series approach is then useful to identify the ideal time window to put in action management measures so that they are cost-effective.

Non-indigenous species contribute equally to biofouling communities in international vs local ports in the Biobío region, Chile.

Growing coastal urbanization together with the intensification of maritime traffic are major processes explaining the increasing rate of biological introductions in marine environments. To investigate the link between international maritime traffic and the establishment of non-indigenous species (NIS) in coastal areas, biofouling communities in three international and three nearby local ports along 100 km of coastline in south-central Chile were compared using settlement panels and rapid assessment surveys. A larger number of NIS was observed in international ports, as expected in these 'invasion hubs'. However, despite a few environmental differences between international and local ports, the two port categories did not display significant differences regarding NIS establishment and contribution to community structure over the studied period (1.5 years). In international ports, the free space could be a limiting factor for NIS establishment. The results also suggest that local ports should be considered in NIS surveillance programs in Chile.

Escapes of non-native fish from flooded aquaculture facilities: the case of Paranapanema River, southern Brazil

Non-native species are a major driver of biodiversity loss. Aquaculture activities play a key role in introductions, including the escape of fishes from fish farm facilities. Here, the impact of flooding due to El Niño rains in 2015/2016 in the Lower and Middle Paranapanema River basin, southern Brazil, was investigated by evaluating fish escapes from 12 fish farms. The flooding resulted in the escape of approximately 1.14 million fishes into the river, encompassing 21 species and three hybrids. Non-native species were the most abundant escapees, especially Oreochromis niloticus (Linnaeus, 1758) and Coptodon rendalli (Boulenger, 1897) (96% of all fish). Only seven native fishes were in the escapee fauna, comprising 1% of all fish. Large floods, coupled with inadequate biosecurity, thus resulted in considerable inputs of non-native fish into this already invaded system.

Escapes of non-native fish from flooded aquaculture facilities: the case of Paranapanema River, southern Brazil

Non-native species are a major driver of biodiversity loss. Aquaculture activities play a key role in introductions, including the escape of fishes from fish farm facilities. Here, the impact of flooding due to El Niño rains in 2015/2016 in the Lower and Middle Paranapanema River basin, southern Brazil, was investigated by evaluating fish escapes from 12 fish farms. The flooding resulted in the escape of approximately 1.14 million fishes into the river, encompassing 21 species and three hybrids. Non-native species were the most abundant escapees, especially Oreochromis niloticus (Linnaeus, 1758) and Coptodon rendalli (Boulenger, 1897) (96% of all fish). Only seven native fishes were in the escapee fauna, comprising 1% of all fish. Large floods, coupled with inadequate biosecurity, thus resulted in considerable inputs of non-native fish into this already invaded system.(AU)

First record of black-tufted marmoset Callithrix penicillata (É. Geoffroy, 1812) (Primates, Callitrichidae) in Northern Paraná, Brazil / Primeiro registro de ocorrência de sagui de tufo preto Callithrix penicillata (É. Geoffroy, 1812) (Primates, Callitrichidae) no norte do Paraná, Brasil

Invasive species always endanger biodiversity because of their competing efficiency for food resources, high reproduction, and dispersion capacity. The aim of this study is to report the first record of 10 specimens of a small-sized primate, Callithrix penicillata, introduced in an Atlantic Rainforest fragment, Northern Paraná, Brazil. Due to their generalist feeding habit, behavior flexibility and parental care, the species adapted itself to different habitat and types of food. The monitoring of the group should be enhanced since the characteristics of the environment which provides them with food and shelter, coupled to the forced placement of the specimens in the fragments, may establish the species in the area.

Espécies invasoras ameaçam a biodiversidade por sua eficiência na competição por recursos e elevada capacidade reprodutiva e de dispersão. O trabalho reporta o primeiro registro de 10 indivíduos de Callithrix penicillata, primata de pequeno porte, introduzidos em um fragmento florestal de Mata Atlântica, no norte do Paraná. Devido ao hábito alimentar generalista, flexibilidade comportamental e cuidado parental, a espécie pode adaptar-se a diferentes habitat e tipos de alimentação. Assim, destaca-se a necessidade de monitorar o grupo, tendo em vista que as características do ambiente, que propiciam alimento e abrigo, e o número de indivíduos liberados como pressão de propágulo na natureza, podem permitir o estabelecimento da espécie na área.

First record of black-tufted marmoset Callithrix penicillata (É. Geoffroy, 1812) (Primates, Callitrichidae) in Northern Paraná, Brazil / Primeiro registro de ocorrência de sagui de tufo preto Callithrix penicillata (É. Geoffroy, 1812) (Primates, Callitrichidae) no norte do Paraná, Brasil

Invasive species always endanger biodiversity because of their competing efficiency for food resources, high reproduction, and dispersion capacity. The aim of this study is to report the first record of 10 specimens of a small-sized primate, Callithrix penicillata, introduced in an Atlantic Rainforest fragment, Northern Paraná, Brazil. Due to their generalist feeding habit, behavior flexibility and parental care, the species adapted itself to different habitat and types of food. The monitoring of the group should be enhanced since the characteristics of the environment which provides them with food and shelter, coupled to the forced placement of the specimens in the fragments, may establish the species in the area.(AU)

Espécies invasoras ameaçam a biodiversidade por sua eficiência na competição por recursos e elevada capacidade reprodutiva e de dispersão. O trabalho reporta o primeiro registro de 10 indivíduos de Callithrix penicillata, primata de pequeno porte, introduzidos em um fragmento florestal de Mata Atlântica, no norte do Paraná. Devido ao hábito alimentar generalista, flexibilidade comportamental e cuidado parental, a espécie pode adaptar-se a diferentes habitat e tipos de alimentação. Assim, destaca-se a necessidade de monitorar o grupo, tendo em vista que as características do ambiente, que propiciam alimento e abrigo, e o número de indivíduos liberados como pressão de propágulo na natureza, podem permitir o estabelecimento da espécie na área.(AU)

Small size today, aquarium dumping tomorrow: sales of juvenile non-native large fish as an important threat in Brazil

Informal sales of large-bodied non-native aquarium fishes (known as "tankbusters") is increasing among Brazilian hobbyists. In this study, we surveyed this non-regulated trade on Facebook® from May 2012 to September 2016, systematically collecting information about the fishes available for trading: species, family, common/scientific names, native range, juvenile length, behavior, number of specimens available in five geographical regions from Brazil. We also assessed the invasion risk of the most frequently sold species using the Fish Invasiveness Screening Test (FIST). We found 93 taxa belonging to 35 families. Cichlidae was the dominant family, and most species were native to South America. All species are sold at very small sizes (< 10.0 cm), and most display aggressive behavior. The hybrid Amphilophus trimaculatus × Amphilophus citrinellus, Astronotus ocellatus, Uaru amphiacanthoides, Osteoglossum bicirrhosum, Cichla piquiti, Pangasianodon hypophthalmus, Datnioides microlepis and Cichla kelberi were the main species available. The southeast region showed the greatest trading activity. Based on biological traits, the FIST indicated that Arapaima gigas, C. kelberi and C. temensis are high-risk species in terms of biological invasions via aquarium dumping. We suggest management strategies such as trade regulations, monitoring, euthanasia and educational programs to prevent further introductions via aquarium dumping.(AU)

A venda de juvenis de peixes não-nativos de grandes dimensões, chamados de "peixes jumbo", está aumentando entre aquaristas no Brasil. Neste trabalho, pesquisou-se este comércio informal pelo Facebook® de maio/2012 a setembro/2016, coletando-se informações sobre espécies, família, nomes vulgares/científicos, origem, tamanho juvenil, comportamento e número/frequência de exemplares disponíveis nas cinco regiões geográficas do Brasil. Também avaliou-se o risco de invasão das espécies mais vendidas usando o protocolo Fish Invasiveness Screening Test (FIST). Foram encontradas 93 espécies pertencentes a 35 famílias. Cichlidae foi a família dominante, e a maioria das espécies é nativa da América do Sul. Todas as espécies foram vendidas como juvenis (< 10.0 cm), e a maioria exibe comportamento agressivo. O híbrido Amphilophus trimaculatus × Amphilophus citrinellus, Astronotus ocellatus, Uaru amphiacanthoides, Osteoglossum bicirrhosum, Cichla piquiti, Pangasianodon hypophthalmus, Datnioides microlepis e Cichla kelberi foram as espécies mais comercializadas. A região sudeste apresentou a maior porcentagem de vendas, e o FIST mostrou que Arapaima gigas, C. kelberi e C. temensis foram consideradas de alto risco para desencadear invasões biológicas mediadas por descarte de aquários. Recomendações como a regulação do comércio, monitoramento, sacrifício das espécies e campanhas educacionais para os aquaristas são sugeridas para evitar futuras introduções de peixes via descarte de aquários.(AU)

Small size today, aquarium dumping tomorrow: sales of juvenile non-native large fish as an important threat in Brazil

Informal sales of large-bodied non-native aquarium fishes (known as "tankbusters") is increasing among Brazilian hobbyists. In this study, we surveyed this non-regulated trade on Facebook® from May 2012 to September 2016, systematically collecting information about the fishes available for trading: species, family, common/scientific names, native range, juvenile length, behavior, number of specimens available in five geographical regions from Brazil. We also assessed the invasion risk of the most frequently sold species using the Fish Invasiveness Screening Test (FIST). We found 93 taxa belonging to 35 families. Cichlidae was the dominant family, and most species were native to South America. All species are sold at very small sizes (< 10.0 cm), and most display aggressive behavior. The hybrid Amphilophus trimaculatus × Amphilophus citrinellus, Astronotus ocellatus, Uaru amphiacanthoides, Osteoglossum bicirrhosum, Cichla piquiti, Pangasianodon hypophthalmus, Datnioides microlepis and Cichla kelberi were the main species available. The southeast region showed the greatest trading activity. Based on biological traits, the FIST indicated that Arapaima gigas, C. kelberi and C. temensis are high-risk species in terms of biological invasions via aquarium dumping. We suggest management strategies such as trade regulations, monitoring, euthanasia and educational programs to prevent further introductions via aquarium dumping.(AU)

A venda de juvenis de peixes não-nativos de grandes dimensões, chamados de "peixes jumbo", está aumentando entre aquaristas no Brasil. Neste trabalho, pesquisou-se este comércio informal pelo Facebook® de maio/2012 a setembro/2016, coletando-se informações sobre espécies, família, nomes vulgares/científicos, origem, tamanho juvenil, comportamento e número/frequência de exemplares disponíveis nas cinco regiões geográficas do Brasil. Também avaliou-se o risco de invasão das espécies mais vendidas usando o protocolo Fish Invasiveness Screening Test (FIST). Foram encontradas 93 espécies pertencentes a 35 famílias. Cichlidae foi a família dominante, e a maioria das espécies é nativa da América do Sul. Todas as espécies foram vendidas como juvenis (< 10.0 cm), e a maioria exibe comportamento agressivo. O híbrido Amphilophus trimaculatus × Amphilophus citrinellus, Astronotus ocellatus, Uaru amphiacanthoides, Osteoglossum bicirrhosum, Cichla piquiti, Pangasianodon hypophthalmus, Datnioides microlepis e Cichla kelberi foram as espécies mais comercializadas. A região sudeste apresentou a maior porcentagem de vendas, e o FIST mostrou que Arapaima gigas, C. kelberi e C. temensis foram consideradas de alto risco para desencadear invasões biológicas mediadas por descarte de aquários. Recomendações como a regulação do comércio, monitoramento, sacrifício das espécies e campanhas educacionais para os aquaristas são sugeridas para evitar futuras introduções de peixes via descarte de aquários.(AU)

Communities of Social Bees (Apidae: Meliponini) in Trap-Nests: the Spatial Dynamics of Reproduction in an Area of Atlantic Forest.

As most stingless bee species depend on preexisting cavities, principally tree hollows, nesting site availability may represent an important restriction in the structuring of their forest communities. The present study examined the spatial dynamics of stingless bee communities in an area of Atlantic Forest by evaluating their swarming to trap-nests. The field work was performed in the Michelin Ecological Reserve (MER) on the southeastern coast of the state of Bahia, Brazil. Seven hundred and twenty trap-nests were distributed within two forest habitats in advanced and initial stages of regeneration. The trap-nests were monitored between September 2009 and March 2011. Twenty-five trap-nests were occupied by five bee species, resulting in a capture ratio of 0.035 swarms/trap (approximately 0.14 swarms/ha), corresponding to 10 swarms/year (0.056 swarms/ha/year). According to previous study at MER, the most abundant species in natural nests were also the most common in trap-nests in the two forest habitats examined, with the exception of Melipona scutellaris Latreille. Swarms of higher numbers of species were captured in initial regeneration stage forests than in advanced regeneration stage areas, and differences in species compositions were significant between both habitats (p = 0.03); these apparent differences were not consistent, however, when considering richness (p = 0.14) and total abundance (p = 0.08). The present study suggests the existence of a minimum cavity size threshold of approximately 1 L for most local species of stingless bees and sustains the hypothesis of a mass effect of Tetragonisca angustula Latreille populations from surrounding disturbed habitats on the MER forest community in terms of propagule (swarm) pressure. Examining swarm densities with trap-nests can be a promising technique for comparative analyses of the carrying capacities of forest habitats for stingless bee colonies, as long as size thresholds of cavities for nesting are taken into consideration.

Propagule pressure, genetic structure, and geographic origins of Chondrilla juncea (Asteraceae): an apomictic invader on three continents.

PREMISE OF THE STUDY: Assessing propagule pressure and geographic origins of invasive species provides insight into the invasion process. Rush skeletonweed (Chondrilla juncea; Asteraceae) is an apomictic, perennial plant that is invasive in Australia, South America (Argentina), and North America (Canada and the United States). This study comprehensively compares propagule pressure and geographic structure of genotypes to improve our understanding of a clonal invasion and enhance management strategies. • METHODS: We analyzed 1056 native range plants from Eurasia and 1156 plants from three invaded continents using amplified fragment length polymorphism (AFLP) techniques. We used measures of diversity (Simpson's D) and evenness (E), analysis of molecular variance, and Mantel tests to compare invasions, and genotype similarity to determine origins of invasive genotypes. • KEY RESULTS: We found 682 unique genotypes in the native range, but only 13 in the invaded regions. Each invaded region contained distinct AFLP genotypes, suggesting independent introduction events, probably with different geographic origins. Relatively low propagule pressure was associated with each introduction around the globe, but levels of among-population variation differed. We found exact AFLP genotype matches between the native and invaded ranges for five of the 13 invasive genotypes. • CONCLUSIONS: Invasion dynamics can vary across invaded ranges within a species. Intensive sampling for molecular analyses can provide insight for understanding intraspecific invasion dynamics, which can hold significance for the management of plant species, especially by finding origins and distributions of invasive genotypes for classical biological control efforts.